Optical coherence tomography (OCT) is a kind of intravascular imaging of coronary arteries, which has become an important tool for accurate clinical optimization of coronary intervention. So, what are the latest developments in OCT in recent years? At the 27th Interventional Cardiology Conference of the Chinese Medical Doctor Association and the 13th China Chest Pain Center Conference (CCIF&CCPCC2024) held recently, Professor Hou Jingbo from the Second Affiliated Hospital of Harbin Medical University gave a wonderful report to answer this question, emphasizing the importance of endovascular imaging technology in the treatment of contemporary complex coronary artery diseases, and sharing the increasing evidence-based evidence to support its application.
Evidence-based medical evidence for OCT
With the accumulation of evidence-based medical evidence, the status of intravascular ultrasound (IVUS) and OCT in clinical application is increasing. A comparative analysis of 31 studies showed that both IVUS and OCT significantly reduced the incidence of major adverse cardiovascular and cerebrovascular events (MACE) compared with conventional contrast techniques. In the comparison between IVUS and OCT, OCT is not inferior to IVUS.
But the most recent impact was a real-time updated network meta-analysis led by Professor Gregg W. Stone, which included two randomized studies of 12,428 randomized patients, combined with the latest OCT study, and showed a significant advantage of endovascular imaging over contrast in reducing target vessel failure rates, with a 31% reduction. This improvement was mainly due to a 46% reduction in cardiac death, a 20% reduction in target myocardial infarction, and a 29% reduction in target vascular reconstruction.
Although the number of interventional treatments in China exceeded 1.6 million in 2023, the mortality rate has not decreased significantly. The main contribution of endoluminal imaging techniques in improving patient outcomes is the relative reduction in cardiac death. In terms of safety, endoluminal imaging significantly reduced the risk of stent thrombosis (52%), all-cause mortality (25%), and all myocardial infarction (18%).
In the latest real-time updated network meta-analysis, OCT and IVUS were compared, and the results showed that there was no significant difference between the two in indicators such as target lesion loss of power (TLF) and cardiac death, indicating that OCT is not inferior to IVUS in interventional treatment guidance.
The OCTIVUS study in South Korea was a head-to-head randomized controlled study comparing OCT and IVUS-guided PCI with a total of 2,008 patients. The one-year event rate was 3.1% and 2.5% in the IVUS and OCT guidance groups, respectively, which were much lower than the 7%-8% of general interventional therapy. Although there was no statistically significant difference, the event rate in the OCT-guided group was consistently lower than in the IVUS-guided group, suggesting that OCT may have an advantage in interventional guidance.
In summary, endovascular imaging technology has shown significant advantages in improving the efficacy and safety of PCI treatment, and OCT is not inferior to IVUS in many indicators, providing strong evidence-based medical support for coronary intervention. At present, endovascular imaging technology has become an important auxiliary tool for decision-making of precision interventional treatment of coronary arteries, and its application has developed from the clinical trial stage to the standardized use recommended by guidelines. Several clinical guidelines have given endoluminal imaging techniques a Level IIa recommendation in specific situations, emphasizing their importance in optimizing stent placement and evaluating in-stent restenosis. The 2023 European Society of Cardiology guidelines for the management of acute coronary syndromes (ACS) further state that the use of endoluminal imaging-guided percutaneous coronary intervention (PCI) should be considered in patients with ACS to improve treatment outcomes. For unclear offender lesions, optical coherence tomography (OCT) is recommended for etiological diagnosis.
Optimize coronary stent implantation throughout the process
1. Preoperative evaluation: accurately assess the characteristics of coronary plaque
In clinical interventional practice, OCT is widely used in preoperative evaluation to accurately assess the characteristics of coronary plaque, especially in the diagnosis of acute coronary syndrome (ACS), OCT has obvious advantages over intravascular ultrasound.
The application of OCT has two main purposes: (1) it is able to distinguish between different types of lesions such as plaque rupture, plaque erosion, or calcified nodules; (2) OCT helps to assess the degree of risk of lesions, so as to guide clinical decisions, including whether to perform interventional therapy, stent implantation, or conservative drug therapy. Therefore, OCT is of great value in both diagnosis and precision treatment guidance.
Professor Yu Bo's team from the Second Affiliated Hospital of Harbin Medical University used OCT to establish a set of criteria to determine the characteristics of criminal lesions, which are used to diagnose plaque rupture, plaque erosion, and other rare causes in ACS. OCT is not only able to diagnose lesions of large coronary arteries, but also to identify atherosclerotic lesions of origin in 61% of non-obstructive myocardial infarctions (MINOCA), as well as spontaneous arterial dissection.
In the field of fragile plaque research, the CLIMA study is a milestone for OCT. The study, which involved 1,003 patients and 1,776 plaques, found that these vulnerable plaques had a 7.54-fold higher rate of adverse events at 12 months than other plaques when the plaques had the following characteristics: a fibrous cap thickness (FCT) of <75 μm, a minimum lumen area (MLA) of 3.5 mm², a maximum lipid angle of <> 180°, and significant macrophage infiltration. Although the positive predictive value of these features needs to be improved, their negative predictive value is high, which provides a basis for clinical intervention.
Professor Hou said that a larger, retrospective study conducted by his center, involving 883 patients and 3,757 non-criminal lesions, was followed for up to four years. The results of the study, which were published in 2023, showed a 15.5-fold increased risk of adverse cardiovascular events in patients with plaques with the following high-risk features: MLA < 3.5 mm², thinnest fiber cap thickness < 67 μm, and maximum lipid angle > 225°. This finding further enhances the application value of OCT in the diagnosis of high-risk plaques.
In addition, another study found that lipid plaques outside the stent were an important cause of recurrent myocardial infarction, increasing the risk of myocardial infarction by a factor of two. However, there is currently no clear intervention threshold (CUT point) for predicting fragile plaque events.
The use of PCSK9 inhibitors has shown positive effects in studies where endoluminal imaging techniques are used to evaluate the effects of certain treatments on atheromas. Both the PACMAN-AMI study and the YELLOW III study demonstrated that high-intensity PCSK9 inhibitor therapy can stabilize or even reverse plaque. This suggests that in the field of plaque reversal, more attention should be paid to when to use interventions such as stent implantation, as well as to find clinical treatments that are of great value for plaque stabilization and reversal.
2. Intraoperative decision-making: guide the standard process of interventional therapy
In terms of the optimization of the whole process of coronary artery stent implantation, a standardized OCT process has been established to guide the implementation of treatment. Studies have shown that interventional treatment relying solely on traditional contrast techniques can lead to up to 38% of stent size misselection. The LATCHlab study further proposes the MLDMax standard, which emphasizes a thorough assessment of plaque properties prior to stent implantation in order to select the appropriate stent length, diameter, and foothold. Doing so avoids the appearance of marginal dissections after implantation and ensures a good fit and adequate expansion of the stent. The Light Lab study showed that the standardized pathway of MLD MAX can change the clinical treatment strategy of 88% of surgeons.
In the Chinese expert consensus released in 2023, a seven-step approach was adopted due to the joint leadership of President Bo and Director Liu Bin. The method involves a thorough preoperative assessment of the lumen and plaque, selection of the appropriate reference segment and stent size. During the stent implantation process, the ACR (Angiography Co-Registration) contrast fusion technique is used to guide the precise implantation. After implantation, ensure a good expansion area of the stent and the fit of the blood vessel wall to avoid complications. Therefore, different levels of pretreatment may be required for different clinical situations, including general, aggressive, and adequate. Thick calcified or calcified nodules that protrude into the lumen of the vessel at more than 180° can be thoroughly pretreated with a combination of rotational atherectomy, endovascular coronary laser plasty (ELCA), and shockwave intravascular lithotripsy (IVL) techniques to optimize stent implantation.
In the standard process of coronary artery stenting, it is critical to choose the right stent foothold and diameter. In addition, for issues such as marginal dissection, poor adhesion, and tissue prolapse, there is a need to clarify the optimization criteria to determine whether further management is required.
In this area, there are two important randomized controlled studies that provide strong evidence for evidence-based medicine.
The ILUMIEN IV study was a large-scale, single-blind, randomized trial that included a total of 2,487 patients. The study has a dual primary endpoint: (1) the primary imaging endpoint: the minimum stent area after PCI was measured by OCT; (2) Primary clinical endpoint: target vessel failure (TVF, defined as cardiogenic death, target vessel myocardial infarction, or ischemia-driven target vessel revascularization) at 2 years. The results showed that the group of patients guided by OCT achieved a statistically significant difference in stent area at the first endpoint. However, no significant differences were shown between the two groups in terms of MACE. MLDMax's standard process follows OCT guidelines with good results. Despite this, the ILUMIEN IV study failed to show a statistically significant difference in clinical endpoints, but careful analysis showed that there was a significant difference between the two groups prior to the pandemic. This suggests that the pandemic may have affected the pattern of care for people with heart disease.
The OCTOBER study is a long-term study involving 1,201 patients at 38 centers. About one-fifth of these cases are bifurcation lesions of the left main, and the rest are bifurcation lesions at other sites. The management of left main bifurcation lesions under OCT guidance is similar to that of other bifurcation lesions. The study highlights the importance of an OCT-guided management of bifurcation lesions, including pre-dilation of the lesion, preoperative OCT assessment, selection of appropriate stent sites, and ensuring that there is 6-8 mm proximal space for proximal optimization technique (POT). Make sure that the stent completely covers the lesion and that the guidewire remains inside the stent at all times. In China, the DKPro technique requires rewire from the proximal end, with the postoperative goal of achieving at least 90% stent inflation and adhesion, avoiding bifurcation displacement, thrombosis, and ensuring optimal area of the branch opening and main branch opening. Following a strict bifurcation procedure, the incidence of MACE over two years was significantly lower in the OCT-guided group than in the contrast-guided group (10.1 versus 14.1 percent, with an absolute difference of 4 percent), showing a statistically significant difference. Therefore, the use of endoluminal imaging techniques for precise guidance, especially for bifurcation lesions and the Rewire guidewire step, can significantly reduce the incidence of adverse events.
ACS "interventional without implantation" concept antithrombotic therapy: stenosis <70%, light plaque load
In the latest evidence-based medical research, especially for the strategy of not implanting stents in the interventional treatment of ACS, the EROSION series of studies has proposed an important conceptual strategy.
The EROSION study suggests that about a quarter of patients with ACS may not require stenting or other interventional procedures. The study found that 25% of patients with acute myocardial infarction had a 70% < luminal stenosis caused by plaques, and after one month of antithrombotic therapy, the amount of thrombus decreased by 94.2% and the lumen diameter increased by 3.6%. Follow-up results showed good clinical outcomes from one month to one year, especially with four-year data showing that 80% of patients were stable with no ischemic events, and only 20% had restenosis or required revascularization. Further analysis of these 20% of patients revealed a large volume of residual thrombus at one month, suggesting that more intensive antithrombotic therapy should be used for patients with plaque initiation.
The EROSION II study further explored whether patients with < 70% of stenosis plaque rupture could also be without stents. The results of the study suggest that no stent implantation may also be considered when 70% of the <stenosis of plaques has a more than 50% reduction in thrombotic burden within one month and the rupture site is trending to heal.
The EROSION II study also explored the value of OCT in guiding treatment. OCT can help doctors prioritize medical therapy over immediate stent implantation when treating patients with ST-elevation myocardial infarction (STEMI), even if the stenosis is not severe. Under the guidance of OCT, the proportion of stents that were not implanted was 25%, which further reduced the stent implantation rate by 15%. The study found that 41% of patients with plaque rupture and 86% of plaque erosion did not require stent implantation, and one year of clinical and radiographic follow-up showed that the treatment was safe and effective.
Based on the latest evidence-based medical evidence from OCT, it can be seen that OCT can guide the whole process of treatment, including preoperative assessment, intraoperative decision-making, postoperative optimization, and whether to choose non-implant interventional therapy. This kind of individualized and accurate treatment guidance is of great significance for improving the treatment effect and quality of life of patients.
Changes in the development of endovascular imaging on the treatment strategy and mode of coronary heart disease
When discussing which endocavity imaging technology is superior, OCT or IVUS, we must recognize that the development trend of endocavity imaging is from single-modal, low-resolution to multi-modal, high-resolution. The combination of multiple imaging modes can provide richer diagnostic information. For example, the Second Affiliated Hospital of Harbin Medical University, under the leadership of President Yu Bo, has developed an integrated optical coherence tomography machine with partners, which has been applied to more than 4,000 patients. As technology continues to advance, this all-in-one imaging device has the potential to surpass traditional large-scale imaging systems.
Another significant trend is that physicians may be able to obtain a large amount of information in a single scan, including data such as IVUS, OCT, and near-infrared spectroscopy (NIRS). This abundance of information bodes well for the future of relying on AI-assisted analysis software systems for endocavity imaging analysis. Such a system can enable rapid diagnosis and strategic judgment to optimize treatment outcomes.
OCT vs Functional
The latest evidence-based medical studies have compared OCT with physiological functional tests such as fractional flow reserve (FFR) in guiding treatment decisions for coronary artery disease. Studies have shown that in clinical practice, for patients with coronary artery stenosis with an FFR value of ≤ 0.8, the use of OCT to guide stent implantation can optimize the treatment effect and may improve the clinical prognosis of patients. In contrast, the FFR-guided treatment group had a higher proportion of patients receiving conservative treatment and lower overall treatment costs.
This finding is further reinforced by the COMMIT (OCT-FFR) study, providing stronger evidence for clinical practice. The study explored the detection of vulnerable plaques by OCT in a patient population with an FFR value of > 0.8. The results of the study showed that patients with vulnerable plaques had a significantly higher incidence of major adverse cardiovascular and cerebrovascular events (MACEs) at 18 months, and this trend was more pronounced at follow-up to 5 years. This suggests that the presence of high-risk plaque features is associated with higher event rates even when FFR values are within normal ranges.
These findings suggest that relying solely on functional tests (e.g., FFR) to guide the treatment of coronary artery disease may not be sufficient. The combination of endoluminal imaging (e.g., OCT) and functional testing can provide a more comprehensive assessment of lesions, so as to more accurately guide treatment strategies and achieve a comprehensive assessment of morphology and function. Future treatment decisions will tend to favor this multimodal integration approach to improve treatment outcomes and optimize patient outcomes.
Expert Profile
Prof. Shizuha
• Director of the Cardiovascular Intervention Center, Deputy Director of the Department of Cardiology, Second-level Professor, Chief Physician and Doctoral Supervisor of the Second Affiliated Hospital of Harbin Medical University
• Changjiang Scholar Distinguished Professor and Longjiang Scholar Distinguished Professor of the Ministry of Education
• Director and PI of the Office of the National Key Laboratory of Cardiovascular Diseases in Cold Regions, Deputy Director of the Key Laboratory of Myocardial Ischemia of the Ministry of Education
• Director of Heilongjiang Provincial Clinical Research Center for Coronary Heart Disease and Arrhythmia
• Winner of the National May Day Women's Pacesetter, the first Longjiang Famous Doctor, and the title of the most beautiful female employee of the Heilongjiang Provincial Federation of Trade Unions
• Member of the Standing Committee of the Cardiovascular Branch of the Chinese Medical Doctor Association
• Deputy Head of the Endoluminal Imaging and Physiology Group of the Cardiovascular Disease Branch of the Chinese Medical Association
• Member of the Thrombosis Group of the Cardiovascular Branch of the Chinese Medical Doctor Association
• Chairman of the Cardiovascular Disease Committee of Heilongjiang Geriatrics Society
• Vice Chairman of the Cardiovascular Professional Committee of Heilongjiang Medical Association
• Vice Chairman of the Cardiovascular Medicine Committee of Heilongjiang Medical Doctor Association
• Vice President of Heilongjiang Heart Society; FACC, FSCAI, etc
Thank you very much for your attention and support to Yimaitong Cardiovascular Platform, please help us complete the following research.
Thank you again for taking the time to participate in our research! If you have any comments or suggestions on "Yimaitong Cardiovascular", you are welcome to leave a message below.
Yimaitong is a professional online doctor platform, and the mission of the platform is to "sense the pulse of the world's medicine and help China's clinical decision-making". Yimaitong has a series of products such as "Clinical Guidelines", "Medication Reference", "Medical Literature King", "Yizhiyuan", "eYantong" and "ePulse", which fully meet the needs of medical workers in clinical decision-making, obtaining new knowledge and improving scientific research efficiency.